1. Field of the Invention
The present invention relates to a notification system, and, in particular, to a notification system which notifies a caller of information about a called mobile station which is in a foreign county.
2. Description of the Related Art
One of the biggest differences between a fixed type telephone and a mobile station such as a mobile phone or a personal handy-phone (PHS) is that a called phone is fixed at a predetermined location or not. A person who makes a call to a fixed telephone can know where the called telephone is from the telephone number of the called telephone. Therefore, the person can predict telephone fee for having telephone conversation with the user of the called telephone.
However, a person who makes a call to a mobile station cannot know where the called phone is at the moment when he or she makes the call. Recently, people are capable of using their mobile phones in foreign countries with the international roaming services. As is disclosed in an international application whose publication number is WO 97/47151, even when a mobile station which belongs to a first country mobile network moves to a foreign country, a connection between a caller and the mobile station is established when the caller dials subscriber number of the mobile station in the first country mobile network.
In such the case, the caller can make a call and have a telephone conversation with the user of the called mobile station without knowing the user of the called mobile station is in a foreign country. As described above, it is very convenient to use the international roaming service, as a caller party and a called party can communicate with each other even when one of the parties is in a foreign country.
However, with the above international roaming system, different from conventional telephone communication system using special number, i.e. country code, for making international call, the caller may unconsciously make a call to a person who is in a foreign country. In such the case, the caller can only know the fact that he or she made the international call after being charged high amount of telephone fees.